#user_list,
#message {
    border: 1px #aaa solid;
    width: 800px;
    margin: 50px auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

#user_list div,
#message>div {
    line-height: 60px;
    display: flex;
    flex-direction: column;
}

#user_list div {
    width: 200px;
    text-align: center;
}

#user_list .active {
    background-color: aqua;
    color: #FFF;
}

.wrap {
    width: 250px;
    border: 1px aqua solid;
    margin-bottom: 20px;
    height: 450px;
    overflow: auto;
}

.wrap>div:first-child {
    line-height: 30px;
}

.wrap .user_masg {
    display: flex;
    justify-content: center;
    align-items: center;
}

.wrap .msg {
    list-style: none;
    margin: 0;
    padding: 0;
    line-height: 25px;
}